I do not think there is comprehensive list published by Disney that lists all of the items that you can get for a snack credit. There is a thread on the
DDP board that has an ongoing list that is very helpful.
http://www.disboards.com/showthread.php?t=2381706
As for guidebooks, my sense would be with how fast things change (or can change) it's probably not worth spending the money on a book. The threads on the board are probably more up to date.
For quick service, there is a Disney brochure for 2010. My understanding is that the 2011 lists are in development, but in most cases the previous year's listings are a good place to start.
http://disneyworld.disney.go.com/me...World/en_us/PDF/2010QuickService_updated2.pdf